"These strong winds, which blow from the land out into the ocean,
cause cold water to rise from the bottom of the ocean to the top,
bringing with it many nutrients that ultimately benefit local
fisheries," said Dr. Timothy Liu, a senior research scientist at
NASA's Jet Propulsion Laboratory, Pasadena, Calif., and Quikscat
project scientist. Santa Ana consequences include vortices of cold
water and high concentrations of chlorophyll 400 to 1,000 kilometers
(248 to 621 miles) offshore.

Liu and Dr. Hua Hu of the California Institute of Technology,
Pasadena, in a paper published last year in Geophysical Research
Letters, revealed satellite observations of the Santa Ana effects on
the ocean during three windy days in February 2003. According to the
findings, Quikscat was able to identify the fine features of the
coastal Santa Ana wind jets. It identified location, strength and
extent, which other weather prediction products lack the resolution to
consistently show, and which moored ocean buoys lack sufficient
coverage to fully represent.

Quikscat's high-resolution images of air-sea interaction were used to
measure wind forces on the ocean. Other satellites and instruments,
like the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the
Advanced Very High Resolution Radiometer, onboard a National Oceanic
and Atmospheric Administration polar orbiting weather satellite, were
used to measure the temperature and biological production of the ocean
surface, which respond to the wind.

The latter instrument showed sea surface temperatures dropped four
degrees Celsius (seven degrees Fahrenheit) during the February 2003
Santa Anas. That was a sign that upwelling had occurred, meaning,
deep cold water moved up to the ocean surface bringing nutrients.
Images from SeaWiFS confirmed the increased biological productivity by
measuring chlorophyll concentrations in the surface water. It went
from negligible, in the absence of winds, to very active biological
activity (more than 1.5 milligrams per cubic meter) in the presence of
the winds.

"There really is no other system that can monitor Santa Ana winds over
the entire oceanic region," Liu said. "Scatterometers such as Quikscat
have a large enough field of view and high enough resolution to easily
identify the details of coastal winds, which can affect the
transportation, ecology and economy of Southern California."

High pressure develops inland when cold air is trapped over the
mountains, driving the dry, hot and dusty Santa Anas (also called
Santanas and Devil's Breath) at high speeds toward the coast. The
winds, occurring in fall, winter and spring, can reach 113 kilometers
(70 miles) per hour. They happen at any time of day and usually reach
peak strength in December. Telltale signs on the coast include good
visibility inland, unusually low humidity and an approaching dark
brown dust cloud.

The Quikscat satellite, launched in June 1999, operates in a
Sun-synchronous, 800-kilometer (497-mile) near-polar orbit. It
circles Earth every 100 minutes and takes approximately 400,000 daily
measurements over 93 percent of the planet's surface. It passes over
Southern California about twice a day, skipping a day every three or
four days.

Quikscat is part of an integrated Earth observation system managed by
NASA's Office of Earth Science. The NASA enterprise is dedicated to
understanding the Earth as an integrated system and applying Earth
System Science to improve prediction of climate, weather, and natural
hazards using the unique vantage point of space.